CBET Infusion Pumps and Medication Delivery Systems — Questions and Answers
Question 1: A syringe pump generates an 'occlusion downstream' alarm. The patient's IV site appears patent. What is the MOST likely next step for a BMET troubleshooting this pump?
- Increase the occlusion pressure detection threshold in the service menu
- Inspect the IV line for kinks, closed clamps, or infiltration at the catheter site (Correct answer)
- Replace the syringe drive mechanism
- Swap the syringe for a new one of identical brand
Correct answer: Inspect the IV line for kinks, closed clamps, or infiltration at the catheter site
A downstream occlusion alarm means the pump's pressure sensor detected resistance distal to the syringe. The most common causes are a clamped or kinked IV line, a closed stopcock, or a failed/infiltrated IV catheter. Adjusting the threshold would mask a real clinical problem, and replacing the drive mechanism is unwarranted before ruling out external causes.
Question 2: What is the primary patient safety advantage of a 'smart pump' drug library (DERS — Dose Error Reduction Software) over a standard volumetric infusion pump?
- Faster priming of the IV tubing
- Automatic recalibration of flow rate accuracy
- Alerting the clinician when a programmed dose falls outside safe soft and hard limits for a specific drug (Correct answer)
- Eliminating the need for secondary QC checks by pharmacy
Correct answer: Alerting the clinician when a programmed dose falls outside safe soft and hard limits for a specific drug
DERS drug libraries contain facility-customized dose limits (soft limits trigger an alert; hard limits prevent programming) for each drug by care area. When a clinician enters a dose, the pump checks it against the library and warns of potential 10-fold errors or protocol deviations. This directly targets programming errors, which are a leading cause of IV medication adverse events.
Question 3: A BMET is performing a flow-rate accuracy check on a volumetric infusion pump using gravimetric testing. For most general-purpose volumetric pumps, what is the acceptable accuracy tolerance per manufacturer and AAMI standards?
- ±1%
- ±5% (Correct answer)
- ±10%
- ±20%
Correct answer: ±5%
AAMI and most pump manufacturers specify ±5% flow rate accuracy as the acceptable tolerance for volumetric infusion pumps under steady-state conditions. This is the standard threshold used in PM protocols. A ±1% tolerance is unrealistic for peristaltic mechanisms; ±10–20% would be clinically unsafe for high-alert medications.
Question 4: Which component of a peristaltic (linear) infusion pump mechanism most directly controls flow rate accuracy and is the most common wear item requiring replacement or inspection during PM?
- The LCD keypad membrane
- The peristaltic fingers or cam mechanism and IV tubing segment (Correct answer)
- The lithium backup battery
- The upstream pressure sensor
Correct answer: The peristaltic fingers or cam mechanism and IV tubing segment
In a linear peristaltic pump, the fingers or cam sequentially compress a dedicated tubing segment to push fluid. As the tubing fatigues (loses elasticity) or the fingers wear, the volume displaced per cycle changes, degrading flow rate accuracy. This is the mechanism by which the pump moves fluid and the component most subject to wear.
Question 5: A patient-controlled analgesia (PCA) pump is programmed with a demand dose of 1 mg morphine, a lockout interval of 10 minutes, and a 4-hour limit of 20 mg. A family member is found pressing the PCA button repeatedly on behalf of the patient. Why is this a critical safety concern the BMET should report?
- It will drain the pump battery faster than normal
- It bypasses the lockout interval because multiple authorized users override the timer
- The 4-hour limit is the only safety barrier, and rapid button presses by a non-patient can deliver that maximum dose to a patient who may not need it, causing respiratory depression (Correct answer)
- The pump will alarm and lock down permanently after unauthorized use
Correct answer: The 4-hour limit is the only safety barrier, and rapid button presses by a non-patient can deliver that maximum dose to a patient who may not need it, causing respiratory depression
PCA therapy is designed around the 'patient' being awake and self-limiting — an opioid-induced sedated patient will stop pressing. A proxy pressing the button can deliver the full 4-hour dose limit to a sedated patient without the natural protective feedback mechanism, risking dangerous respiratory depression. The lockout still applies per press, but the 4-hour ceiling can still be reached.
Question 6: When calculating an infusion rate for a weight-based norepinephrine drip (e.g., 0.1 mcg/kg/min) for a 70 kg patient using a concentration of 4 mg in 250 mL NS, what is the correct rate in mL/hr?
- 26.25 mL/hr (Correct answer)
- 10.5 mL/hr
- 6.3 mL/hr
- 4.2 mL/hr
Correct answer: 26.25 mL/hr
Concentration = 4 mg / 250 mL = 16 mcg/mL = 16,000 mcg/250 mL. Rate (mL/hr) = Dose (mcg/kg/min) × Weight (kg) × 60 min/hr ÷ Concentration (mcg/mL) = 0.1 × 70 × 60 ÷ 16 = 420 ÷ 16 = 26.25 mL/hr. BMETs must verify pump programming using this formula as part of safety checks during rounds.
CBET Infusion Pumps and Medication Delivery Systems
A syringe pump generates an 'occlusion downstream' alarm.
The patient's IV site appears patent.
What is the MOST likely next step for a BMET troubleshooting this pump?